Peach tree—named ‘White Rock’ cultivar

ABSTRACT

Description and specifications of a new and distinct peach variety which originated from seed produced by a hand pollinated cross of Ark. 371 (non-patented) and Ark. 367 (non-patented) is provided. This new peach variety can be distinguished by its features of early mid-season ripening, high yields of high-quality, attractive, clingstone, very firm white-flesh fruits, and good plant vigor along with good resistance to bacterial spot disease.

Botanical classification: Genus/species: Prunus persica.

Cultivar: ‘White Rock’.

SUMMARY OF THE INVENTION

The new and distinct variety of peach originated from a hand-pollinatedcross of Ark. 371 (non-patented)×Ark. 367 (non-patented) made in 1993 atthe University of Arkansas Fruit Substation, Clarksville. The femaleparent plant used in this hybridization (Ark. 371) is a veryfirm-fruited with a somewhat crisp flesh texture white peach selectionwith other characters including clingstone pit adherence, low-acidflavor, medium fruit size and ripens approximately July 20. The maleparent (Ark. 367) is a first, non-melting flesh type white peach with amore rubbery texture as found in canning-cling type fruits, and is alsoa clingstone, large fruited, and ripens about July 1. Neither parentselection has been publicly released and nor are they available incommerce. The instant variety differs from one or both parents in thatit ripens approximately June 25, has a low-acid flavor, medium fruitsize and a very firm, semi-crisp flesh texture. Both the parents and theinstant variety are the genus and species Prunus persica.

The seeds resulting from this controlled hybridization were germinatedin a greenhouse in the late winter 1993/early spring of 1994 and plantedin a field on the University of Arkansas Fruit Substation, Clarksville,Ark. The seedlings fruited during the summer of 1997 and one, designatedArkansas 658, was selected for its very firm white flesh, earlymid-season ripening, large fruits, attractive fruit appearance, goodfruit quality with low-acid flavor, and resistance to bacterial spot.During 1997, the original plant selection was propagated asexually, atthe above-noted location, by budding onto standard peach rootstockvariety ‘Lovell’ (non-patented) and a test plot of two plants wasestablished. Subsequently, larger test plantings have been establishedwith asexually multiplied plants at two additional locations in Arkansas(Clarksville and Hope, Ark.).

The new variety has been asexually multiplied several times since 1997at this location by budding onto ‘Lovell’ peach rootstock and noincompatibility with peach rootstocks has occurred following budding.During all asexual multiplication, the characteristics of the originalplant have been maintained and no aberrant phenotypes have appeared.

Plants of the new variety are vigorous and productive, and trees arestandard in size, well-branched and symmetrical with an upright tosemi-spreading growth habit, comparable to other peach trees (Prunuspersica). Trees express a moderate level of resistance to both foliarand fruit infection of bacterial spot [Xanthomonas campestris pv. pruni(Smith) Dye] but in some years do not show complete immunity to thisdisease. The new variety consistently is more resistant to bacterialspot than is the standard white peach variety ‘Carolina Belle’ (notpatented). The new variety blooms on approximately the same date as‘Carolina Belle’ and ‘Stark® Summer Pearl™’ (not patented). No wintercold injury has been observed on wood or buds of the new variety inArkansas tests where minimum temperatures have reached −13° C. duringevaluation. Chilling requirement to break dormancy is estimated to be750 hours below 7° C.

Fruit of the new variety ripens early mid-season, averaging 15 daysbefore ‘Carolina Belle’ and 30 days before ‘Stark® Summer Pearl™’reference white peach varieties. Average first ripening date is June 25in west-central Arkansas (Clarksville). Fruit of the new variety has notbeen observed to have split pits, a serious fruit disorder of some peachvarieties. Fruit yields have been good and have averaged higher than ornear equal those of the comparison peach varieties ‘Carolina Belle’, and‘Stark® Summer Pearl™’ in test comparisons.

The fruit is round to slightly oval in shape, without a prominent tipbut with a pronounced suture bulge. Fruits are attractive with anaverage 72% bright red blush, and 28% white or cream skin backgroundcolor. In some years the red blush was up to 80% of the fruit skinsurface, especially when fruits are exposed to more sunlight than thosefruits growing in the shaded canopy. Fruit finish is good with noblemishes. The fruit skin has average pubescence like other peaches. Theflesh of the fruit is white in color and has slight red pigment in theflesh, mostly around the stone or pit. Flesh is non-melting to crisp intexture and is very firm and retains firmness after full maturity. Thefruit is a clingstone, in that the flesh adheres to the pit. Fruit sizeis medium-large averaging 154 g.

The fresh fruit rates very good in flavor, and was rated highly inevaluations. Fruits average 12.2% soluble solids. The flavor is sweetand low-acid, with a light white peach aroma.

The distinctive features of the new variety are its early mid-seasonripening, high yields of high-quality, attractive, clingstone, very firmwhite-flesh fruits, and good plant vigor along with good resistance tobacterial spot disease.

The new variety has been named the ‘WHITE ROCK’ cultivar.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying photographs show typical specimens of the fruit (FIGS.1 and 2) and leaf (FIG. 3) of the new variety in color as nearly true asit is reasonably possible to make in a color illustration of thischaracter.

DETAILED BOTANICAL DESCRIPTION OF THE NEW VARIETY

The following is a detailed description of the botanical and pomologicalcharacteristics of the subject peach. Color data are presented in RoyalHorticultural Society Colour Chart designations.

Where dimensions, sizes, colors and other characteristics are given, itis to be understood that such characteristics are approximations ofaverages set forth as accurately as practical.

The descriptions reported herein are from specimens grown atClarksville, Ark. and are from trees grown in trickle (drip) irrigatedorchards growing on a Linker fine sandy loam soil. The data werecollected from six-year old trees of the instant variety except yielddata that were taken on five-year-old trees in a replicated testplanting.

-   Plant:    -   -   Size.—Mature trees (6 years of age and older) average 3.2 m            to 3.5 m in height and 4.7 to 5.8 m in spread or width, and            a semi-upright growth habit; as grown on ‘Lovell’ rootstock            using an open-center training system commonly used on            peaches. Tree size is comparable to that of the ‘Carolina            Belle’ and ‘Stark® Summer Pearl™’ varieties.        -   Growth.—Vigorous, symmetrical form, good canopy development.            Vigor comparable to that of the ‘Carolina Belle’ and ‘Stark®            Summer Pearl™’ varieties.        -   Productivity.—Productive and consistent from year to year.            Yield measured 25.5 kg/tree on five year-old trees trained            to a perpendicular V training system, exceeding that of            ‘Carolina Belle’ with 20.8 kg/tree and 11.0 kg/tree for            ‘Summer Pearl’™.        -   Cold hardiness.—Wood and dormant buds hardy to −13° C.;            hardiness may exceed this level as this was the lowest            temperature the trees were exposed to during testing.        -   Disease resistance.—Leaves and fruit resistant but not            immune to bacterial spot under growing conditions where            bacterial spot infection is often very severe on susceptible            genotypes. No bactericides were used in the development or            evaluation of the instant cultivar. Evidence of bacterial            spot infection was less than that of ‘Carolina Belle’ in all            years of evaluation. A commercial fungicide program was            utilized in orchards used in the development and evaluation            of the instant variety, thus no resistance to brown rot or            peach scab, the other common diseases at Clarksville, Ark.,            was determined.        -   Insect resistance.—Insecticides were applied to orchards            used in the development of the instant variety to control            the common insects at the location including oriental fruit            moth, plum curculio, stinkbug, tarnished plant bug, lesser            peach tree borer, and greater peach tree borer. Therefore no            insect resistance was determined in the testing of the            instant variety.-   Foliage/shoots/branches:    -   -   Shoots.—Smooth. Current growing-season mature shoot length            42.6 cm; diameter base 0.52 cm, midpoint 0.38 cm, terminal            0.28 cm (measured in July of the growing season).            Dormant-season shoot (branch): length 42.6 cm; diameter at            base 0.56 cm; diameter at midpoint 0.41 cm; diameter at            terminal 0.29 cm. Dormant-season shoot color Greyed-Purple            Group (183B); Dormant-season shoot texture smooth.        -   Leaves.—Simple, alternate, glabrous, lanceolate, petiolate,            deciduous. Venation pinnate; base acute; terminal or apex            acuminate; margin serrated. Mature leaf size: length 15.8            cm; width midpoint 4.0 cm. Leaf serrations; 4.4/cm. Mature            leaf color: abaxial — Yellow-Green Group (146B); adaxial —            Yellow-Green Group (137B); and anthocyanin not present on            abaxial or adaxial side of mature leaves on midrib or other            location. Young leaf color: abaxial — Yellow-Green Group            (146B); adaxial — Yellow Green Group (146A); anthocyanin not            present on abaxial or adaxial side of young leaves on midrib            or other location. Petiole length — mature leaf: 1.1 cm.            Leaf glands: reniform, 2 per leaf usually, located on basal            portion of leaf blade. Leaf glands are 0.06 cm in width and            0.12 cm in length.        -   Buds.—Number of leaf buds per 15 cm: 8.4 evenly distributed            along the shoot. Number of flower buds per 0-15 cm from            terminal: 12.6. Mature shoot internode length between buds:            base 1.4 cm, midpoint 1.8 cm, terminal 1.1 cm.-   Bark (of mature trunk of tree):    -   -   Color.—Greyed-Green Group (197B).        -   Texture.—Rough.-   Trunk:    -   -   Diameter.—14 cm (at 25 cm above ground level).-   Flower buds: Dormant flower bud length 0.4 cm and diameter 0.2 cm    and color Greyed-Orange Group (166A); dormant buds swell and expand    in late winter and increase in size during this expansion to fully    open flowers. Color changes to that of the adaxial petal color    Red-Purple Group (65C).-   Flowers: Bloom occurs prior to vegetative bud break; solitary to    occasional double individual flowers at a single node; perfect;    self-fertile.    -   -   Date of bloom.—First, Julian 80 (March 20); Full, Julian 87            (March 27).        -   Size.—Diameter fully open 3.9 cm.        -   Type.—Showy.        -   Color.—Adaxial — Red-Purple Group (65C); abaxial —            Red-Purple Group (65D).        -   Petals per flower.—5.        -   Length of pistil.—1.7 mm.        -   Stamens.—Average 48/flower with pollen present, fertile and            abundant.-   Fruit:    -   -   Size.—Med-large, avg. 154 g; diameter stem end 4.8 cm,            equator 6 cm, blossom end 4.0 cm; length base to apex 5.7            cm.        -   Shape.—Round to oval. Fruits are without pronounced tip but            have a pronounced suture bulge.        -   Skin.—Pubescent (fuzzy), attractive; ground color Yellow            Group (11B), with red blush (Red Group 46A; 47 D), over 72%            of surface on average.        -   Flesh.—Yellow-White Group (158C); cling; non-melting            texture; exceptional firmness. Firmness when measured by a            fruit pressure tester (using a McCormick model FT327 fruit            pressure tester, 11 mm diameter probe, McCormick Fruit Tree            Co., Yakima, Wash.) on unpeeled fruit had average firmness            value of 6.2 kg. Good eating quality; flavor sweet,            low-acid, with light white peach flavor and aroma.        -   Pedicel length.—0.7 cm.        -   Pedicel diameter.—0.4 cm.        -   Pedicel color.—Yellow-Green Group (144C).        -   Ripe date.—First ripe June 25 (Julian 177) in west-central            Arkansas. Ripening of individual fruit is uniform.        -   Tendency of pit to split.—No split pits observed.        -   Soluble solids.—12.2%.        -   Fruit juice pH.—4.82.-   Pit/stone:    -   -   Size.—Length 3.4 cm; diameter (midpoint) 2.1 cm.        -   Shape.—Slightly oblong with deep furrowing and pitting.        -   Color.—Greyed-Orange Group (167C).-   Kernel:    -   -   Size.—Length 1.5 cm; diameter varies with dryness of the            kernel but is up to 0.4 cm.        -   Shape.—Almond shaped.        -   Color.—Greyed-Orange Group (163A).-   Uses: Fresh consumption, not evaluated for drying or other uses.    The Variety

The most distinctive features of the new variety are its earlymid-season ripening, high yields of high-quality, attractive,clingstone, very firm white-flesh fruits, and good plant vigor alongwith good resistance to bacterial spot disease.

1. A new and distinct variety of peach tree (Prunus persica cultivar‘White Rock’) as herein described and illustrated, characterized by itsearly mid-season ripening, high yields of high-quality, attractive,clingstone, very firm white-flesh fruits, and good plant vigor alongwith good resistance to bacterial spot disease.